Ecology Of Species Interactions 3 — Questions and Answers
Question 1: The concept of an 'ecological trap' occurs when:
- Prey species hide in dense vegetation
- A habitat cue attracts organisms to poor-quality environments (Correct answer)
- Predators set ambushes near water sources
- Competing species force each other into suboptimal niches
Correct answer: A habitat cue attracts organisms to poor-quality environments
An ecological trap arises when environmental cues mislead organisms into preferring low-quality or dangerous habitats.
Question 2: Batesian mimicry is best defined as:
- A toxic species mimicking another toxic species
- A harmless species mimicking a dangerous or unpalatable species (Correct answer)
- Two harmless species converging on the same appearance
- A predator mimicking its prey to ambush victims
Correct answer: A harmless species mimicking a dangerous or unpalatable species
In Batesian mimicry, a palatable mimic gains protection by resembling an unpalatable or dangerous model species.
Question 3: Which outcome is predicted by the competitive exclusion principle?
- Two species with identical niches will stably coexist
- Two species competing for identical resources cannot coexist indefinitely (Correct answer)
- Competition always leads to evolution of new species
- Interspecific competition is always stronger than intraspecific competition
Correct answer: Two species competing for identical resources cannot coexist indefinitely
Gause's competitive exclusion principle states that two species occupying identical niches cannot coexist; one will be excluded.
Question 4: A parasitoid differs from a true parasite primarily because the parasitoid:
- Lives outside rather than inside its host
- Eventually kills the host as part of its life cycle (Correct answer)
- Has no negative effect on host fitness
- Can infect multiple host species simultaneously
Correct answer: Eventually kills the host as part of its life cycle
Parasitoids ultimately kill their hosts (typically insects) as they complete development, unlike true parasites that usually keep hosts alive.
Question 5: The 'enemy release hypothesis' proposes that invasive species succeed because they:
- Outcompete natives through superior resource use alone
- Leave behind their natural predators, parasites, and pathogens (Correct answer)
- Evolve rapidly to exploit new food sources
- Form mutualistic relationships with native species immediately
Correct answer: Leave behind their natural predators, parasites, and pathogens
Enemy release hypothesis argues that invasive species thrive partly because their coevolved natural enemies are absent in the new range.
Question 6: Which interaction type is most likely to increase both species' population sizes simultaneously?
- Competition
- Predation
- Parasitism
- Mutualism (Correct answer)
Correct answer: Mutualism
Mutualism benefits both partners (+/+), so populations of both species can grow or stabilize as a result of the interaction.
Question 7: In the Lotka-Volterra predator–prey model, what happens to prey population size when the predator population reaches its maximum?
- Prey population is at its maximum
- Prey population is at its minimum
- Prey population is declining most rapidly (Correct answer)
- Prey population size is independent of predator numbers
Correct answer: Prey population is declining most rapidly
When predator numbers peak, prey are being consumed at the highest rate, so the prey population is declining most steeply.
Ecology Of Species Interactions 3
The concept of an 'ecological trap' occurs when: